Simple Rails App：错误无法访问整数 [英] Simple Rails App: Error Cannot visit Integer

问题描述

我正在尝试构建一个简单的Rails应用。 Rails v3.2.22.5（这是必需的）。我在PostgreSQL上运行它。但是，当我启动服务器时，尝试从数据库中读取一个简单的帖子时出现以下错误。

I am trying to build a simple Rails app. Rails v3.2.22.5 (it is a requirement). I am running it with PostgreSQL. When I start the server however I get the following error when I try to read a simple Post from the database.

无法访问整数

Cannot visit Integer

跟踪将我带到下面的show方法。更具体地讲第二行。我是Rails的新手，对于如何解决此问题绝对不了解。已在网上搜索失败。任何想法都将受到欢迎。

The trace leads me to the show method below. More specifically to the second line. I am very new to Rails and have absolutely no clue as to how to fix this. Searched the web already without success. Any ideas would be most welcome.

  def show
    @post = Post.find(params[:id])
    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @post }
    end
  end

完整跟踪：

arel (3.0.3) lib/arel/visitors/visitor.rb:25:in `rescue in visit'
arel (3.0.3) lib/arel/visitors/visitor.rb:19:in `visit'
arel (3.0.3) lib/arel/visitors/to_sql.rb:241:in `visit_Arel_Nodes_Limit'
arel (3.0.3) lib/arel/visitors/visitor.rb:19:in `visit'
arel (3.0.3) lib/arel/visitors/to_sql.rb:123:in `visit_Arel_Nodes_SelectStatement'
arel (3.0.3) lib/arel/visitors/visitor.rb:19:in `visit'
arel (3.0.3) lib/arel/visitors/visitor.rb:5:in `accept'
arel (3.0.3) lib/arel/visitors/to_sql.rb:19:in `accept'
activerecord (3.2.22.5) lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `to_sql'
activerecord (3.2.22.5) lib/active_record/connection_adapters/abstract/query_cache.rb:60:in `select_all'
activerecord (3.2.22.5) lib/active_record/querying.rb:38:in `block in find_by_sql'
activerecord (3.2.22.5) lib/active_record/explain.rb:41:in `logging_query_plan'
activerecord (3.2.22.5) lib/active_record/querying.rb:37:in `find_by_sql'
activerecord (3.2.22.5) lib/active_record/relation.rb:171:in `exec_queries'
activerecord (3.2.22.5) lib/active_record/relation.rb:160:in `block in to_a'
activerecord (3.2.22.5) lib/active_record/explain.rb:34:in `logging_query_plan'
activerecord (3.2.22.5) lib/active_record/relation.rb:159:in `to_a'
activerecord (3.2.22.5) lib/active_record/relation/finder_methods.rb:381:in `find_first'
activerecord (3.2.22.5) lib/active_record/relation/finder_methods.rb:122:in `first'
app/controllers/posts_controller.rb:16:in `show'
actionpack (3.2.22.5) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.2.22.5) lib/abstract_controller/base.rb:167:in `process_action'
actionpack (3.2.22.5) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (3.2.22.5) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.2.22.5) lib/active_support/callbacks.rb:414:in `_run__2562463311931153568__process_action__1655262725222060869__callbacks'
activesupport (3.2.22.5) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.22.5) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
activesupport (3.2.22.5) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.22.5) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.2.22.5) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (3.2.22.5) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.2.22.5) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.22.5) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.22.5) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.22.5) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.2.22.5) lib/action_controller/metal/params_wrapper.rb:207:in `process_action'
activerecord (3.2.22.5) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (3.2.22.5) lib/abstract_controller/base.rb:121:in `process'
actionpack (3.2.22.5) lib/abstract_controller/rendering.rb:46:in `process'
actionpack (3.2.22.5) lib/action_controller/metal.rb:203:in `dispatch'
actionpack (3.2.22.5) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.2.22.5) lib/action_controller/metal.rb:246:in `block in action'
actionpack (3.2.22.5) lib/action_dispatch/routing/route_set.rb:73:in `dispatch'
actionpack (3.2.22.5) lib/action_dispatch/routing/route_set.rb:36:in `call'
journey (1.0.4) lib/journey/router.rb:68:in `block in call'
journey (1.0.4) lib/journey/router.rb:56:in `each'
journey (1.0.4) lib/journey/router.rb:56:in `call'
actionpack (3.2.22.5) lib/action_dispatch/routing/route_set.rb:608:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.4.7) lib/rack/etag.rb:23:in `call'
rack (1.4.7) lib/rack/conditionalget.rb:25:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/head.rb:14:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/flash.rb:242:in `call'
rack (1.4.7) lib/rack/session/abstract/id.rb:210:in `context'
rack (1.4.7) lib/rack/session/abstract/id.rb:205:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/cookies.rb:341:in `call'
activerecord (3.2.22.5) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.2.22.5) lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.22.5) lib/active_support/callbacks.rb:405:in `_run__2325253408966325104__call__3112622970942194936__callbacks'
activesupport (3.2.22.5) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.22.5) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.22.5) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.22.5) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.22.5) lib/rails/rack/logger.rb:32:in `call_app'
railties (3.2.22.5) lib/rails/rack/logger.rb:16:in `block in call'
activesupport (3.2.22.5) lib/active_support/tagged_logging.rb:22:in `tagged'
railties (3.2.22.5) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.4.7) lib/rack/methodoverride.rb:21:in `call'
rack (1.4.7) lib/rack/runtime.rb:17:in `call'
activesupport (3.2.22.5) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.7) lib/rack/lock.rb:15:in `call'
actionpack (3.2.22.5) lib/action_dispatch/middleware/static.rb:83:in `call'
railties (3.2.22.5) lib/rails/engine.rb:484:in `call'
railties (3.2.22.5) lib/rails/application.rb:231:in `call'
rack (1.4.7) lib/rack/content_length.rb:14:in `call'
railties (3.2.22.5) lib/rails/rack/log_tailer.rb:17:in `call'
rack (1.4.7) lib/rack/handler/webrick.rb:59:in `service'
/Users/luishreis/.rbenv/versions/2.4.1/lib/ruby/2.4.0/webrick/httpserver.rb:140:in `service'
/Users/luishreis/.rbenv/versions/2.4.1/lib/ruby/2.4.0/webrick/httpserver.rb:96:in `run'
/Users/luishreis/.rbenv/versions/2.4.1/lib/ruby/2.4.0/webrick/server.rb:290:in `block in start_thread'

推荐答案

您使用的Ruby版本（2.4.1）与您使用的Rails版本（3.2.22.5）不兼容。该版本的Ruby至少需要Rails5。尝试降级到Ruby 2.3或更低版本。您可以使用Ruby版本管理器（即 rvm ， rbenv 或 chruby ）来控制在启动应用程序时使用哪种Ruby。

The version of Ruby you're using (2.4.1) is not compatible with the version of Rails you're using (3.2.22.5). That version of Ruby requires at least Rails 5. Try downgrading to Ruby 2.3 or lower. You can use a Ruby version manager (i.e. rvm, rbenv or chruby) to control which Ruby is used when launching your application.

只是注意到您已经从堆栈跟踪中使用 rbenv 了。将 .ruby-version 文件添加到应用程序目录中，其中包含以下行：

Just noticed you're already using rbenv from your stack trace. Add a .ruby-version file to your application's directory containing the following line:

2.3.4

重新进入该目录后，请通过以下方式确认版本：

Once you re-enter that directory, confirm the version via:

$> ruby -v
ruby 2.3.4p301 (2017-03-30 revision 58214) [x86_64-darwin16]

（或类似版本），然后再启动滑轨。

(or similar version) before launching rails.

这篇关于Simple Rails App：错误无法访问整数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！